title: Cerebrospinal fluid lactate in post-neurosurgical bacterial meningitis diagnosis.
abstract: BACKGROUND
  Differential diagnosis between post-neurosurgical bacterial meningitis (PNBM) and aseptic meningitis is difficult. Inflammatory and biochemical cerebrospinal fluid (CSF) changes mimic those classically observed after CNS surgery. CSF lactate assay has therefore been proposed as a useful PNBM marker.
  
  
  OBJECTIVE
  To evaluate the diagnostic accuracy of CSF lactate as a PNBM marker in patients hospitalized after a neurosurgical procedure.
  
  
  METHODS
  Between July 2005 and June 2009, a prospective clinical study, in which all patients with clinical suspicion of PNBM were enrolled, was conducted at our neurosurgical Intensive Care Unit. PNBM diagnosis was categorized as proven, probable or negative before the analysis.
  
  
  RESULTS
  Seventy-nine patients, 51 males with a mean age of 50 years (range 32-68 years) were included. Surgery was elective in 76% patients, mostly for brain tumors (57%); thirty PNBM episodes were identified. CSF parameters were significantly different in glucose concentration (27 mg% vs. 73 mg%, p<0.001), lactate (8 mmol/L vs. 2.8 mmol/L, p<0.001), CSF neutrophil pleocytosis (850 mm(-3) vs. 10mm(-3), p<0.001), and protein levels (449 mg% vs. 98 mg%) between the PNBM and non-PNBM groups. The ROC curve that best fits PNBM diagnosis is lactate.
  
  
  CONCLUSIONS
  Increased CSF lactate is a useful PNBM marker, with better predictive value than CSF hypoglycorrhachia or pleocytosis. Lactate levels ≥ 4 mmol/L showed 97% sensitivity and 78% specificity, with a 97% negative predictive value.
authors.affiliation: Intensive Care Unit, Raúl Carrea Neurological Research Institute, FLENI, Buenos Aires, Argentina. p_maskin@yahoo.com
authors.forename: Luis Patricio
authors.initials: LP
authors.lastname: Maskin
authors.forename: Federico
authors.initials: F
authors.lastname: Capparelli
authors.forename: Andrea
authors.initials: A
authors.lastname: Mora
authors.forename: Alejandro
authors.initials: A
authors.lastname: Hlavnicka
authors.forename: Nora
authors.initials: N
authors.lastname: Orellana
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Díaz
authors.forename: Néstor
authors.initials: N
authors.lastname: Wainsztein
authors.forename: Marcelo
authors.initials: M
authors.lastname: Del Castillo
mesh_terms: D000328:Adult; D000368:Aged; D019072:Antibiotic Prophylaxis; D003627:Data Interpretation, Statistical; D003937:Diagnosis, Differential; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D007427:Intracranial Pressure; D019344:Lactic Acid / Q000134:cerebrospinal fluid*; D008297:Male; D008582:Meningitis, Aseptic / Q000134:cerebrospinal fluid; D016920:Meningitis, Bacterial / Q000134:cerebrospinal fluid* / Q000209:etiology* / Q000382:microbiology; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects*; D011183:Postoperative Complications / Q000134:cerebrospinal fluid* / Q000209:etiology* / Q000382:microbiology; D011446:Prospective Studies; D012372:ROC Curve; D013129:Spinal Puncture
chemical_list: D019344:Lactic Acid
keywords: Bacterial meningitis; CSF lactate; Neurosurgery; Postoperative infection